Coiled, perfusion balloon catheter

ABSTRACT

A perfusion balloon catheter includes an inflatable balloon formed by a series of loops of a flexible, inflatable tube in a generally cooperative tubular shape. The loops are supported by a coiled support member and are locked within the coiled support member by a wire retainer. The cooperative tubular shape of the individual loops perform to provide an inflatable cooperative outer surface of the balloon and a perfusion passage within the balloon.

BACKGROUND OF THE INVENTION

The present invention relates to the field of angioplasty. Inparticular, the present invention relates to a balloon catheter whichpermits prolonged inflation of the balloon within a blood vessel, suchas a coronary artery, without blocking blood flow by utilizing passiveperfusion.

Angioplasty has gained wide acceptance as an efficient, effective andalternative method of treating constrictions caused by undesirous tissuegrowth or lesions on the inner walls of the blood vessels. Such tissuegrowth or lesions cause a narrowing of the blood vessels called a"stenosis" which severely restricts or limits the flow of blood. In themost widely used form of angioplasty, a dilatation catheter, which hasan inflatable balloon at its distal end, is guided through the vascularsystem. With the aid of fluoroscopy, a physician is able to position theballoon across the stenosis. The balloon is then inflated by applyingfluid pressure through an inflation lumen of the catheter to theballoon. Inflation of the balloon stretches the artery and presses thestenosis-causing lesion into the artery wall to remove the constrictionand re-establish acceptable blood flow through the artery.

One disadvantage of many balloon catheters of the prior art is thecomplete occlusion of the blood vessel that results while the balloon isinflated. Prolonged complete blockage of a blood vessel poses seriousrisk of damage to the tissue, downstream from the occlusion, which isdeprived of oxygenated blood. This consequence poses a severe limitationon the length of time the balloon can remain expanded within an arteryto effectively treat the stenosis. Longer inflation times increase theprobability that the artery will remain open after the catheter isremoved.

Various methods for providing passive perfusion of blood through or pastthe inflated balloon are found in the following prior art references:Guiset U.S. Pat. No. 4,183,102; Baran et al. U.S. Pat. No. 4,423,725;Sahota U.S. Pat. No. 4,581,017; Hershenson U.S. Pat. No. 4,585,000;Horzewski et al. U.S. Pat. No. 4,771,777; Mueller et al. U.S. Pat. No.4,790,315; Songer et al. U.S. Pat. No. 4,892,519; Goldberger U.S. Pat.No. 4,909,252; Sogard et al. U.S. Pat. No. 4,944,745; Sahota U.S. Pat.No. 4,983,167 and European patent application 0 246 998; Boussignac etal. U.S. Pat. No. 5,000,734; Patel U.S. Pat. No. 5,000,743; and BonzelU.S. Pat. No. 5,002,531.

A disadvantage of prior tubular-shaped, perfusion balloon catheters isthe additional manufacturing steps necessary to connect outer and innerskins of the balloon to create a perfusion passage between the up-streamside of the balloon and the down-stream side of the balloon. Anotherdisadvantage is the risk of interrupted integrity of the balloon at theseams created by the connection of outer and inner skins. Additionally,tubular-shaped balloons of the prior art are relatively stiff due to theseams and internal support structures. There is still a need in thefield, therefore, for a balloon catheter with good flexibility and aperfusion cavity which, when inflated within an artery, permits goodarterial blood flow, and yet is capable of being manufactured withrelative ease and minimal cost.

SUMMARY OF THE INVENTION

The present invention is a perfusion balloon catheter which includes ashaft with a shaft lumen, a support structure which extends distallyfrom a distal end of the shaft, and a balloon formed by a flexible,inflatable tube carried by the support structure. The perfusion ballooncatheter of the present invention uses a coiled support member, as thesupport structure, to hold a series of adjacent loops of the flexibletube and thereby form a composite balloon having a tubular shape. Adistal end of the coiled, flexible tube is sealed, and a proximal end ofthe flexible tube is in fluid communication with the shaft lumen.

The balloon formed by the tube loops, when inflated, has an outersurface which interacts with the wall of the artery, and an innersurface which defines a passive perfusion passage. The present inventionpermits prolonged inflation of the balloon during a dilatation procedurewhile reducing the risk of tissue damage distal to the balloon location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a first embodiment of the perfusion ballooncatheter of the present invention.

FIG. 2 is a side view, partially in section, of the distal end of thecatheter of FIG. 1.

FIG. 3 is a longitudinal sectional view of the balloon assembly.

FIG. 4 is a sectional view of the balloon assembly taken along line 4--4of FIG. 2.

FIG. 5 is a cross sectional view of the balloon assembly taken alongline 5--5 of FIG. 3.

FIG. 6 is a cross sectional view of the balloon assembly taken alongline 6--6 of FIG. 3.

FIG. 6A is a view of the balloon assembly of FIG. 6 shown with adilatation balloon.

FIG. 7 is an enlarged side view, partially in section, of a secondembodiment of the present invention.

FIG. 8 is a longitudinal sectional view of the balloon assembly of FIG.7.

FIG. 9 is an end view of the balloon assembly taken from line 9--9 ofFIG. 7.

FIG. 10 is a side view, partially in section, of a third embodiment ofthe present invention.

FIG. 11 is a longitudinal sectional view of the balloon assembly shownin FIG. 10.

FIG. 12 is an end view of the balloon assembly taken from line 12--12 ofFIG. 10.

FIG. 13 is an enlarged side view, partially in section, of a fourthembodiment of the present invention.

FIG. 14 is a longitudinal sectional view of the balloon assembly of FIG.13.

FIG. 15 is an end view of the balloon assembly taken along line 15--15of FIG. 13.

FIG. 16 is an enlarged side view, partially in section, of a fifthembodiment of the present invention.

FIG. 17 is a longitudinal sectional view of the balloon assembly of FIG.16.

FIG. 18 is a side view of the coiled support member of the balloonassembly.

FIG. 19 is an enlarged side view of the coiled support member, mandriland initial position of the flexible tube.

FIG. 20 is a side view of the coiled support member, mandril, andflexible tube looped once around the coiled support member and mandril.

FIG. 21 is a side view of the coiled support member, mandril, and seriesof loops of the flexible tube around the coiled support member andmandril.

FIG. 22 is a side view of the coiled support member, mandril, and tubeloops with the flexible tube inflated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. The FirstEmbodiment (FIGS. 1-6)

FIG. 1 shows a side view of perfusion balloon catheter 10, whichincludes manifold 12, elongated tubular shaft 14, balloon assembly 16,and guide wire 18.

Manifold 12 is located at the proximal end of catheter 10. Manifold 12includes inflation port 20, through which inflation fluid is provided toand withdrawn from inflatable multiple-loop composite balloon 22 ofballoon assembly 16.

Elongated tubular shaft 14 of catheter 10 is a single lumen tube havingits proximal end 24 connected to manifold 12 and its distal end 26connected to balloon 22 of balloon assembly 16. Shaft lumen 27 (shown inFIG. 2), which extends through shaft 14 from proximal end 24 to distalend 26, is in fluid communication with inflation fluid port 20 ofmanifold 12, and also with balloon 22 of balloon assembly 16.

In preferred embodiments, shaft 14 possesses the qualities ofcompression rigidity along the longitudinal axis, which facilitatesadvancement of catheter 10 through the vascular system, and good distalflexibility, which enhances maneuverability of catheter 10 throughdirectional changes of the vascular system. These qualities areachievable in a variety of ways. In one embodiment, the proximal regionof shaft 14 is a stainless steel hypo tube, and the distal region is apolyethylene tube which is connected to the proximal region. In anotherembodiment, shaft 14 is formed from a single piece of polymer tubingwith a proximal region that has an outer and inner diameter larger thanan outer and inner diameter of a distal region.

Guide wire 18 is external to and proximate to shaft 14 and runs theentire length of catheter 10. Guide wire 18 ends, at its distal end,with guide wire spring tip 18A. Catheter 10 is movable longitudinallyover guide wire 18.

In FIG. 2, an enlarged side view of distal end 26 of shaft 14 andballoon assembly 16 is shown. Balloon assembly 16 includes coiledsupport member 28, inflatable tube 30 (which forms balloon 22) andretainer 32.

Coiled support member 28 has its proximal end mounted within flareddistal end 26 of shaft 14 and extends distally from distal end 26.Adjacent coils of coiled support member 28 are spaced apart to hold tube30 in a looped configuration along coiled support member 28. The distalend of coiled support member 28 terminates in a series of reduceddiameter tight coils which form spring tip 34 of catheter 10. Coiledsupport member 28 is made of any flexible material capable of beingformed into a coil, such as a metal wire or ribbon. Alternatively, otheropen support structures, such as an open-braided/strand-woven tube, canalso hold tube 30 in a looped configuration.

Flexible tube 30 is a flexible, inflatable polyolefin copolymermaterial, such as Surlyn 8527 from Dupont, and cooperates with coiledsupport member 28 to form balloon 22. As shown in FIGS. 2-4, proximalend 36 of flexible tube 30 is located within flared distal end 26 ofshaft 14. Distal end 38 of flexible tube 30 is sealed and is locatednear the distal end of coiled support member 28. Tube lumen 40 extendsthrough tube 30 from proximal end 36 to distal end 38.

Proximal neck region 42 of flexible tube 30 is located within flareddistal end 26, and has a smaller outer diameter and larger wallthickness than the remainder of tube 30. Tube 30 extends through thelongitudinal interior of coiled support member 28 until tube 30 passesout of flared distal end 26 of shaft 14. Adhesive 44 fills a portion ofthe cavity within flared distal end 26 to attach the proximal portionsof coiled support member 28, tube 30 and retainer 32 to shaft 14.

In the embodiment shown in FIGS. 2-6, the portion of tube 30 whichextends distally out of flared distal end 26 is threaded between everyother coil of coiled support member 28 and passes under upper extent 28Aof every other coil of coiled support member 28 to form a series ofinflatable, side-by-side loops 46. When inflation fluid from shaft lumen27 is supplied to tube lumen 40, loops 46 inflate and cooperate to formballoon 22 (as illustrated in FIGS. 2-6).

Loops 46 are captured within coiled support member 28 by retainer 32.Retainer 32 is preferably a wire which extends from shaft 14 throughcoiled support member 28 and spring tip 34. Proximal end 32A of retainer32 lies within shaft 14 and extends proximal to flared distal end 26 toshaft 14. Distal end 32B of retainer 32 is attached to distal end 34A ofspring tip 34. Retainer 32 is positioned between the bottom of each loop46 and lower extents 28B of the coils of coiled support member 28. Loops46, therefore, are captured between retainer 32 and upper extents 28A ofthe coils. Retainer 32 thus serves to retain each tube loop 46 in afixed position along coiled support member 28 while providing structuralsupport to balloon assembly 16 at the distal end of catheter 10.

In order to ensure that loops 46 act as a unit, the tops of loops 46 areconnected together by adhesive 48. Alternatively, loops 46 can be fixedtogether by applying a flexible coating over loops 46. The plurality oftube loops 46 define a generally tubular shaped balloon 22 having acomposite outer surface 50 and a composite inner surface 52. Outersurface 50 applies a radially outward force to an artery wall whenballoon 22 is inflated. Inner surface 52 defines perfusion passage 54which extends through the length of balloon 22.

As shown in FIG. 6A, dilatation balloon D is coincidentally disposed atdistal end 26 of shaft 14, within the perfusion passage 54 to enhancethe radial outward force of outer surface 50. Dilatation balloon D(which is similar to a balloon of a dilatation balloon catheter shown inU.S. Pat. No. 4,943,278) has outer surface O, core wire W and innercavity C which is in fluid communication with lumen 27 of shaft 14.Alternatively, dilatation balloon D can be disposed at a distal end of acatheter shaft which has separate inflation lumens, or at a distal endof a second catheter shaft. Dilatation balloon D is inflated withballoon 22 such that outer surface O of dilatation balloon D contactsinner surface 52 of perfusion passage 54, causing an outward radialforce of dilatation balloon D to be transmitted to composite outersurface 50 of balloon 22. With the artery wall expanded by the compositeoutward radial force of balloon 22 and dilatation balloon D, dilatationballoon D is deflated to permit the flow of blood through perfusionpassage 54 while balloon 22 remains inflated within the artery.Alternatively, dilatation balloon D may be moved proximal to balloon 22to permit the flow of blood through perfusion passage 54.

The cross-sectional area of perfusion passage 54, which ranges fromabout 16 to about 44 percent of the cross-sectional area of compositeouter surface 50, permits a flow of blood through balloon 22 whileballoon 22 is inflated within the artery. Perfusion passage 54 is largeenough to coincidentally serve as a guide passage for guide wire 18.Because balloon 22 is very short compared to the total lengths ofcatheter 10 and guide wire 18, the use of perfusion passage 54 as aguide passage permits rapid exchange of catheter 10 over guide wire 18while guide wire 18 remains in place in the artery with the distal endof guide wire 18 in position across the stenosis.

FIG. 5 shows a cross-sectional view of a proximal portion of balloonassembly 16. For purposes of illustration, adhesive 44 is not shown inFIG. 5. Coiled support member 28 is shown within flared distal end 26.Flexible tube 30 is positioned within coiled support member 28. Retainer32 is positioned below tube 30 and between coiled support member 28 andtube 30.

As illustrated in both FIGS. 5 and 6, inner surface 52 of loop 46defines perfusion passage 54, which also serves as a guide passage forguide wire 18. Guide wire 18 has an unrestricted range of motion withinthe entire perfusion passage 54. Perfusion passage 54 readily providesan avenue for blood flow during a dilatation procedure whilecoincidentally serving as a passage for guide wire 18.

Catheter 10 shown in FIGS. 1-6A is capable of being used with guide wire18 (over-the-wire rapid exchange use) or without guide wire 18(stand-alone use as a fixed wire catheter). Without guide wire 18,spring tip 34 permits use of catheter 10 as a fixed wire catheter.

2. The Second Embodiment (FIGS. 7-9)

FIGS. 7-9 show a second embodiment of the present invention which isgenerally similar to the first embodiment shown in FIGS. 1-6. Similarreference characters are used to designate similar elements.

This second embodiment differs from the first embodiment in that distalregion 70 of flexible tube 30 transitions back within coiled supportmember 28 at the distal end of balloon 22. Coiled support member 28extends distally beyond balloon 22, as shown in FIGS. 7 and 8. Distalregion 70 of tube 30 extends distally through the longitudinal interiorof several coils of coiled support member 28, and then extends outcoiled support member 28 to form guide loop 72 at the distal end ofcoiled support member 28. Distal end 38 of tube 30 is bound to adistal-most coil of coiled support member 28 to seal the distal end oftube lumen 40.

Guide loop 72 has inner and outer diameters which are smaller than theinner and outer diameters of loops 46 of balloon 22. Guide loop 72defines distal guide passage 74 for guide wire 18.

Distal guide passage 74 is generally aligned with perfusion passage 54of balloon 22. Guide wire 18 extends through perfusion passage 54 anddistal guide passage 74 and out the distal end of guide loop 72. Thereduced dimensions of guide loop 72 relative to loops 46 restricts therange of transverse movement of guide wire 18 and directs guide wire 18closer to catheter spring tip 34.

3. The Third Embodiment (FIGS. 10-12)

FIGS. 10-12 show a third embodiment of the present invention. This thirdembodiment is similar to the embodiment shown in FIGS. 1-6 except thatcatheter spring tip 34 is extended and guide wire support sleeve 100 ismounted on spring tip 34. In FIGS. 10-12, reference characters similarto those used in FIGS. 1-6 are used to designate similar elements.

Guide wire support sleeve 100 is positioned over spring tip 34 with thedistal end of guide wire support sleeve 100 generally aligned withdistal end 34A of spring tip 34. An inner surface of guide wire supportsleeve 100 is bonded by adhesive 102 to spring tip 34. Guide passage 104of sleeve 100 is located distally of perfusion passage 54. Guide wire 18extends through perfusion passage 54 and guide passage 104 and out thedistal end of guide wire support sleeve 100.

4. The Fourth Embodiment (FIGS. 13-15)

FIGS. 13-15 show a fourth embodiment of the present invention. Thisembodiment differs from previous embodiments primarily by virtue ofguide wire tube 120, which extends from distal end 26 of shaft 14through coiled support member 28'. Coiled support member 28', therefore,is larger in diameter than coiled support member 28 of the previousembodiments.

Flexible tube 30 is made of a flexible tubular material and cooperateswith coiled support member 28' to form balloon 22. Flexible tube 30includes proximal neck region 42, which is bonded within distal end 26of shaft 14 by adhesive 44. Tube lumen 40 of flexible tube 30 is influid communication with shaft lumen 27.

Flexible tube 30 extends out of distal end 26 and into coiled supportmember 28'. Tube 30 forms a plurality of inflatable loops 46 which areheld in place between coiled support member 28' and retainer 32. Loops46 cooperate to form inflatable balloon 22.

Guide wire tube 120 has a length approximately equal to the length ofcoiled support member 28', and is positioned within coiled supportmember 28' below tube 30 and adjacent to retainer 32. The lower outersurface of guide wire support tube 120 contacts the lower inner surfaceof coiled support member 28'. Guide wire tube 120 and retainer 32 aremaintained within coiled support member 28' by a bonding material, suchas epoxy. The inner diameter of guide wire tube 120 defines guide wirelumen 122 for passage of guide wire 18.

The proximal end of coiled support member 28' is adjacent to flareddistal end 26 of catheter shaft 14. The proximal end of guide wire tube120 generally abuts flared distal end 26, with an upper internal surface124 of guide wire tube 120 generally aligned with a lower externalsurface 126 of flared distal end 26. The proximal end of guide wire tube120 therefore provides access for guide wire 18 external to cathetershaft 14. The location of guide wire tube 120 distal and external tocatheter shaft 14 permits a physician performing a dilatation procedureto make a rapid catheter exchange of one size perfusion balloon catheterfor another.

In this particular embodiment, a separate catheter spring tip (like tips34 of the first three embodiments) is not used. The catheter of FIGS.13-15 is intended for over-the-wire use, and a separate spring tip isnot required.

5. The Fifth Embodiment (FIGS. 16 and 17)

FIGS. 16 and 17 show a fifth embodiment of the present invention. Thisembodiment differs from the other embodiments primarily by virtue ofguide wire tube 150, and distal end adhesive 152.

As shown in FIGS. 16 and 17, guide wire tube 150 is positioned primarilywithin coiled support member 28". Proximal end 150A of tube 150 islocated adjacent distal end 26 of shaft 14 and proximal to the proximalend of coiled support member 28". Tube 150 extends distally beyond thedistal end of coiled support member 28". Tube 150 defines guide lumen154 for guide wire 18.

Loops 46 of tube 30, which form balloon 22, are captured at their lowerextremes between tube 150 and retainer 32. Retainer 32 extends fromwithin shaft 14, through coiled support member 28" and into distal endguide 152. Retainer 32 is positioned adjacent to and above lower extents28B of each coil of coiled support member 28".

Distal end adhesive 152 is disposed on distal end 150B of guide wiretube 150, distal end 32B of retainer 32 and the distal end of coiledsupport member 28" to secure tube 150, retainer 32 and coiled supportmember 28" at the distal end of catheter 10. The distal end of adhesive152 is aligned with distal end 150B and is generally tapered from itsproximal to its distal end to provide a streamlined profile of thedistal end of catheter 10.

The balloon assembly shown in FIGS. 16 and 17 is bonded within distalend 26 of shaft 14. Proximal neck region 42 of tube 30 and proximal end32A of retainer 32 are inserted within shaft lumen 27 at distal end 26of shaft 14 with the proximal end of coiled support member 28" generallyabutting distal end 26 of shaft 14. Retainer 32 extends into shaft lumen27 of shaft 14 a distance greater than tube 30 and serves to supportballoon assembly 16 and provide distal shaft pushability. Proximal neckregion 42 and proximal end 32A of retainer 32 are bonded within distalend 26 of shaft 14 by adhesive 44. Lumen 40 of flexible tube 30 is influid communication with shaft lumen 27 and provides a means forinflating and deflating loops 46 of balloon 22.

Proximal end 150A of guide wire tube 150 is positioned adjacent to andabove distal end 26 of shaft 26 upon installation of the balloonassembly 16 onto shaft 26. In a preferred embodiment, proximal end 150Aand distal end 26 are bonded together (e.g., by an adhesive) in thepiggyback configuration shown in FIGS. 16 and 17.

6. The Method of Manufacture (FIGS. 18-22)

FIGS. 18-22 show the components and the steps necessary to manufactureballoon assembly 16 of the embodiments shown in FIGS. 1-12. For purposesof this description, the method of manufacture will be described asproceeding from the proximal to the distal end of coiled support member28.

As shown in FIGS. 18-22, an uninflated length of flexible tube 30 isinserted at the proximal end of coiled support member 28. Mandril 170 ispositioned above and adjacent to the outer surface of coiled supportmember 28. Tube 30 is threaded through a side of coiled support member28 as shown in FIG. 19. Tube 30 is wrapped in a distal direction aroundmandril 170 and coiled support member 28, and threaded between adjacentcoils of coiled support member 28. Slight tension is then applied totube 30 to secure tube 30 under upper extent 28A of a coil of coiledsupport member 28. Tube 30 is repeatedly looped in the fashion justdescribed to form a series of inflatable, side-by-side loops 46. WhileFIG. 21 shows tube 30 passing between every other coil of coiled supportmember 28, spacings of tube 30 may vary depending on the size of thetubing or the coiled support member used. The distal end of tube 30 isthen secured to the distal end of coiled support member 28 to sealdistal end 38 of tube 30. Retainer 32 is then threaded through thelength of coiled support member 28 between the bottom side of each tubeloop 46 and lower extents 28B to lock tube loops 46 within coiledsupport member 28.

With mandril 170 in place, tube 30 is heated to about 80° Celsius forabout thirty seconds. Air pressure is applied to the open proximal end36 of tube to cause tube 30 and loops 46 to inflate and expand the outerdiameter of tube 30. Tube 30 is then cooled in a room-temperature waterbath, the air pressure is removed, and the support mandril 170 isremoved. Balloon assembly 16 is then disposed at the distal end ofcatheter shaft 14 (not shown) according to the methods shown for thevarious embodiments in FIGS. 1-17.

Balloon assembly 16 of the embodiment shown in FIGS. 13-15 ismanufactured similar to the embodiments shown in FIGS. 1-12 with oneexception: the placement and location of guide wire tube 120 withincoiled support member 28' succeeds placement of retainer 32.

Balloon assembly 16 of the embodiment shown in FIGS. 16-17 is alsomanufactured similar to the embodiments shown in FIGS. 1-12, except thelocation and placement of guide wire tube 150 within coiled supportmember 28" precedes the wrapping of tube 30 around mandril 170 andcoiled support member 28". Loops 46 of tube 30 are therefore securedbeneath guide wire tube 150.

7. Conclusion

The perfusion balloon of the present invention is simply constructed atan efficient manufacturing cost. The helical tube creates a generallytubular-shaped perfusion balloon which, unlike prior art tubular-shapedperfusion balloons, requires no additional intra-cavity structuralsupport to create and maintain the perfusion passage during ballooninflation. In addition, the perfusion balloon of the present inventionhas fewer seams than previous tubular-shaped perfusion balloons whichincreases flexibility of the distal end of the catheter. Finally, theperfusion balloon of the present invention possesses a perfusion passagewith a cross-sectional area which is between about 16 to 44 percent ofthe cross-sectional area of the inflated balloon. This permits theperfusion balloon of the present invention to remain inflated within theartery while allowing good blood flow through the perfusion passage.

While use of a dilatation balloon with a perfusion balloon catheter ofthe present invention has been described only with reference to thefirst embodiment, such use is incorporated by reference to embodiments 2through 5. Additionally, as well known in the art, radiopaque materialis incorporated into each embodiment of the present invention as amarker to permit a physician to monitor the advancement and positioningof the catheter.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A perfusion balloon catheter comprising:anelongated tubular shaft having a proximal end, a distal end and a lumenextending therethrough; a helical coil of flexible, inflatable tubedisposed at the distal end of the tubular shaft, the tube having aproximal end in fluid communication with the lumen and having a sealeddistal end, the helical coil forming a composite outer surface andcomposite inner surface which define an inflatable tubular-shapedballoon, the composite inner surface further defining a perfusionpassage; a longitudinally-extending support structure through which thetube is looped to form the balloon; and retainer means for securing thetube to the support structure.
 2. The perfusion balloon catheter ofclaim 1 wherein the support structure is a coiled support member.
 3. Theperfusion balloon catheter of claim 2 wherein the retainer meansincludes a wire which extends through the coiled support member tocapture loops of the tube in the coiled support member.
 4. The perfusionballoon catheter of claim 3 wherein a first length of tube is inside thecoiled support member.
 5. The perfusion balloon catheter of claim 4wherein the proximal end of the tube is positioned within the shaftlumen.
 6. The perfusion balloon catheter of claim 5 wherein a secondlength of the tube extends outside of the coiled support member and islooped around the coiled support member to form a plurality of adjacentloops which cooperate to form the inflatable balloon.
 7. The perfusionballoon catheter of claim 6 wherein the tubular-shaped balloon has aninner diameter which is larger than an outer diameter of the coiledsupport member thereby forming the perfusion passage, which extends froma proximal end to a distal end of the balloon.
 8. The perfusion ballooncatheter of claim 7 and further comprising means for connecting adjacentloops of the tubular-shaped balloon.
 9. The perfusion balloon catheterof claim 7 wherein the perfusion passage has an opening, upon inflationof the balloon, with a cross-sectional area of greater than about 15percent of a total cross-sectional area of the opening and the balloon.10. The perfusion balloon catheter of claim 2 wherein the retainer meansis positioned between each loop of the tube and an inner surface of thecoiled support member.
 11. The perfusion balloon catheter of claim 2wherein the tubular shaft includes an outer surface, an inner surfaceand an opening at the distal end of the shaft and wherein the coiledsupport member includes an outer surface and a proximal end, the openingand the inner surface of the distal end of the tubular shaft conformablyaccepting the outer surface of the proximal end of the coiled supportmember, the proximal end of the coiled support member bonded within thedistal end of the tubular shaft.
 12. A perfusion balloon cathetercomprising:an elongated tubular shaft having a proximal end, a distalend, and a shaft lumen which extends from the proximal to the distalend; a balloon support extending distally from the distal end of theshaft, the balloon support including a helical wire coil; and aflexible, inflatable tube having a proximal end in fluid communicationwith the shaft lumen and having a sealed distal end, the inflatable tubebeing wound over the helical wire coil to form a plurality of adjacentloops which, upon inflation of the tube, form a composite balloon havingan outer surface for applying outward force to a vessel wall and aninner surface for defining a fluid passage through the balloon to permitperfusion while the balloon is inflated.
 13. The perfusion ballooncatheter of claim 12 wherein the balloon support furtherincludes:retainer means for holding the inflatable tube in the helicalwire coil.
 14. The perfusion balloon catheter of claim 12 and furthercomprising:a guide wire external and adjacent to the shaft; and guidemeans external to and extending distally from the shaft for engaging theguide wire to permit longitudinal movement of the balloon along theguide wire.
 15. The perfusion balloon catheter of claim 12 wherein thefluid passage, when the balloon is inflated, has an opening which has across-sectional area which is greater than about 15 percent of a totalcross-sectional area of the opening and the balloon.
 16. A perfusionballoon catheter comprising:an elongated tubular shaft having a proximalend, a distal end and an inner surface which defines a lumen from theproximal end to the distal end, the lumen further being exposed by anopening at the distal end of the shaft; a helical coil of flexible,inflatable tube disposed at the distal end of the tubular shaft to forman inflatable tubular-shaped balloon, the tube having a proximal end influid communication with the lumen and having a sealed distal end; alongitudinally-extending support structure through which the tube islooped to form the balloon, wherein the support structure is a coiledsupport member having an outer surface, a proximal end and a distal end;and retainer means for securing the tube to the support structure,wherein the retainer means includes a wire which extends through thecoiled support member to capture loops of the tube in the coiled supportmember.
 17. The perfusion balloon catheter of claim 16 wherein a firstlength of tube is inside the coiled support member.
 18. The perfusionballoon catheter of claim 17 wherein the proximal end of the tube ispositioned within the shaft lumen.
 19. The perfusion balloon catheter ofclaim 18 wherein a second length of the tube extends outside of thecoiled support member and is looped around the coiled support member toform a plurality of adjacent loops which cooperate to form theinflatable balloon.
 20. The perfusion balloon catheter of claim 19wherein the loops form the tubular-shaped balloon having an innerdiameter which is larger than an outer diameter of the coiled supportmember thereby forming a perfusion passage extending from a proximal endto a distal end of the balloon.
 21. The perfusion balloon catheter ofclaim 20 and further comprising means for connecting adjacent loops ofthe tubular-shaped balloon.
 22. The perfusion balloon catheter of claim20 wherein the perfusion passage has an opening, upon inflation of theballoon, with a cross-sectional area of greater than about 15 percent ofa total cross-sectional area of the opening and the balloon.
 23. Theperfusion balloon catheter of claim 16 wherein the retainer means ispositioned between each loop of the tube and an inner surface of thecoiled support member.
 24. The perfusion balloon catheter of claim 16wherein the opening and the inner surface of the distal end of thetubular shaft conform to accept the outer surface of the proximal end ofthe coiled support member, and wherein the proximal end of the coiledsupport member is bonded within the distal end of the tubular shaft. 25.A rapid exchange perfusion balloon catheter for use with a guide wire,the catheter comprising:an elongated tubular shaft having a proximalend, a distal end and a lumen extending therethrough; a tubular-shapedballoon formed by a helical coil of flexible, inflatable tube disposedat the distal end of the tubular shaft, the tube having a proximal endin fluid communication with the distal end of the shaft and having asealed distal end, the balloon having a perfusion passage through acentral region of the helical coil; means connected to the distal end ofthe shaft and extending distally of the distal end of the shaft forretaining the helical coil of flexible tube in a shape of the balloon;and guide means external to the shaft for engaging the guide wire topermit longitudinal movement of the balloon along the guide wire, theguide means associated with the means for retaining the helical coil offlexible tube.
 26. The catheter of claim 25 wherein the guide means is atube having a proximal end, a distal end and a guide wire lumenextending therethrough.
 27. The catheter of claim 25 wherein a proximalend of the flexible tube is bonded within the distal end of the tubularshaft.
 28. The catheter of claim 25 wherein the means for retaining thetube includes a helical wire coil around which the tube is looped toform the balloon.
 29. The catheter of claim 28 wherein the guide meansis positioned within the helical wire coil.
 30. The catheter of claim 25wherein the guide means is a loop of the flexible tube positioneddistally of the balloon.
 31. The catheter of claim 25 wherein theperfusion passage has an opening, upon inflation of the balloon, with across-sectional area which is greater than about 15 percent of a totalcross-sectional area of the opening and the balloon.
 32. A rapidexchange perfusion balloon catheter for use with a guide wire, thecatheter comprising:an elongated tubular shaft having a proximal end, adistal end and a lumen extending therethrough; a tubular-shaped balloonformed by a helical coil of flexible, inflatable tube disposed at thedistal end of the tubular shaft, the tube having a proximal end bondedwithin and in fluid communication with the distal end of the shaft andhaving a sealed distal end, the balloon having a perfusion passagethrough a central region of the helical coil; means connected to thedistal end of the shaft for retaining the helical coil of flexible tubein a shape of the balloon; and guide means external to and associatedwith the shaft for engaging the guide wire to permit longitudinalmovement of the balloon along the guide wire, wherein the guide means isa tube having a proximal end, a distal end and a guide wire lumenextending therethrough.
 33. The catheter of claim 32 wherein the meansfor retaining the tube includes a helical wire coil around which thetube is looped to form the balloon.
 34. The catheter of claim 33 whereinthe guide means is positioned within the helical wire coil.
 35. Thecatheter of claim 32 wherein the guide means is a loop of the flexibletube positioned distally of the balloon.
 36. The catheter of claim 32wherein the perfusion passage has an opening, upon inflation of theballoon, with a cross-sectional area which is greater than about 15percent of a total cross-sectional area of the opening and the balloon.37. A method of sustaining an opening of a blood vessel so as to allowflow of blood through the blood vessel, the method comprising:(a)providing a perfusion balloon which includes: an elongated tubular shaftwith an inflation lumen; an open support structure which extendsdistally from the distal end of the shaft; and an inflatable balloondisposed at the distal end of the shaft and in fluid communication withthe inflation lumen, the balloon being formed by a flexible, inflatabletube which is looped through the support structure to form an inflatablehelical coil having a perfusion passage through a central region of thehelical coil; (b) advancing the perfusion balloon catheter into theblood vessel until the balloon is positioned at a desired locationwithin the blood vessel; and (c) inflating the balloon so as to cause anouter composite surface of the helical coil to expand and contact a wallof the blood vessel and thereby maintain, for an extended period, a flowof blood through the perfusion passage with the balloon inflated. 38.The method of claim 37 and further comprising:positioning a secondinflatable balloon within the central region of the helical coil;inflating the second inflatable balloon to apply a radial outward forcethrough the helical coil to the blood vessel; and deflating the secondinflatable balloon to allow blood flow through the perfusion passage.39. The method of claim 37 wherein advancing the perfusion ballooncatheter includes:inserting a guide wire into the blood vessel; andadvancing the perfusion balloon catheter through the blood vessel alonga path defined by the guide wire.